NATURAL SELECTION 143 



which is all that concerns us. But still there are many 

 hermaphrodite animals which certainly do not habitually 

 pair, and a vast majority of plants are hermaphrodites. 

 What reason, it may be asked, is there for supposing in 

 these cases that two individuals ever concur in reproduc- 

 tion ? As it is impossible here to enter on details, I 

 must trust to some general considerations alone. 



In the first place, I have collected so large a body of 

 facts, and made so many experiments, showing, in ac- 

 cordance with the almost universal belief of breeders, 

 that ^ith animals and plants a__^osj._..hetween„_dififerent 

 varieties, or between individuals of the same j^ariety.. but. 

 of another strain, giyes..,„yi^or and fertility to the_^jB£.- 

 spring; and, on the other hand, that cZose interbreeding 

 diminishes vigor and fertility; that these facts alone 

 incline me to believe that it is a general law of nature 

 jthat-jj(0_organic being fertilizes itself for a perpetuity of 

 generations; but that a cross with another individual is 

 occasionally — perhaps at long intervals of time — indis- 

 pensable. 



On the belief that this is a law of nature, we can, I 

 think, understand several large classes of facts, such as 

 the following, which on any other view are inexplicable. 

 Every hybridizer knows how unfavorable exposure to wet 

 is to the fertilization of a flower, yet what a multitude of 

 flowers have their anthers and stigmas fully exposed to 

 the weather! If an occasional cross be indispensable, 

 notwithstanding that the plant's own anthers and pistil 

 tstand so near each other as almost to insure self-fertiliza- 

 tion, the fullest freedom for the entrance of pollen from 

 another individual will explain the above state of ex- 

 posure of the organs. Many flowers, on the other hand, 



